The broad, long term objective of the proposed research is the development of Optical Doppler Tomography (ODT) for application in the clinical management of patients requiring the use of rotational or free flaps. Information provided bt ODT can a) determine tissue perfusion and viability preoperatively; b) confirm intraoperatively the perfusion and viability of such flaps during transposition; and c) monitor tissue perfusion and viability postoperatively. ODT also offers a means to determine the efficacy of pharmacological interventions for failing flaps or replants. The specific aims of this proposal are to 1) confirm in animal models that ODT can be used to characterize the underlying skin microcirculation at discrete spatial locations in either the superficial or deep dermis; and 2) demonstrate in clinical trials how ODT can be used to a) construct a three-dimensional tomographic image of human skin; and more importantly b) provide guidance in patients requiring microvascular monitoring when the use of rotational or free flaps is necessary for wound closure.